CA1297936C - Electronic ballast for fluorescent lamps - Google Patents
Electronic ballast for fluorescent lampsInfo
- Publication number
- CA1297936C CA1297936C CA000606557A CA606557A CA1297936C CA 1297936 C CA1297936 C CA 1297936C CA 000606557 A CA000606557 A CA 000606557A CA 606557 A CA606557 A CA 606557A CA 1297936 C CA1297936 C CA 1297936C
- Authority
- CA
- Canada
- Prior art keywords
- capacitor
- branches
- switch
- inverter
- inductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
- H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S315/00—Electric lamp and discharge devices: systems
- Y10S315/05—Starting and operating circuit for fluorescent lamp
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S315/00—Electric lamp and discharge devices: systems
- Y10S315/07—Starting and control circuits for gas discharge lamp using transistors
Landscapes
- Circuit Arrangements For Discharge Lamps (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
- Glass Compositions (AREA)
- Furan Compounds (AREA)
- Inverter Devices (AREA)
- Organic Insulating Materials (AREA)
- Discharge Heating (AREA)
- Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
- Rectifiers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Electronic ballasts are essentially composed of a series connection of a harmonic filter that has its input side connected to the AC line, a rectifier and an inverter to which is connected at least one load circuit composed of a series circuit of an inductor and a parallel circuit composed of a fluorescent tube and a capacitor. When a high electric tolerance is required of such a ballast in view of a desired increase in the power factor, standard circuit designs required a relatively expensive storage capacitor that smooths the AC rectified line voltage. In order to be able to use a storage capacitor that has a lower electric tolerance in comparison to the required voltage tolerance of the ballast, a storage capacitor is incorporated into one of the two capacitor branches of the inverter which is composed of a switch bridge arrangement having two switch branches and two capacitor branches, this storage capacitor being connected in series with the actual load.
Electronic ballasts are essentially composed of a series connection of a harmonic filter that has its input side connected to the AC line, a rectifier and an inverter to which is connected at least one load circuit composed of a series circuit of an inductor and a parallel circuit composed of a fluorescent tube and a capacitor. When a high electric tolerance is required of such a ballast in view of a desired increase in the power factor, standard circuit designs required a relatively expensive storage capacitor that smooths the AC rectified line voltage. In order to be able to use a storage capacitor that has a lower electric tolerance in comparison to the required voltage tolerance of the ballast, a storage capacitor is incorporated into one of the two capacitor branches of the inverter which is composed of a switch bridge arrangement having two switch branches and two capacitor branches, this storage capacitor being connected in series with the actual load.
Description
~2~793~i BACKGROUND OF THE INVENTION
The present inven~ion is directed to an electronic ballast for fluorescent lamps, and in particular electronic ballasts having an inverter that has its input side connected to an AC source via a series connection of a harmonic filter and of a rectifier. Such an electronic ballast has lts output side connected to at leas-t one load circuit composed of a series circuit of an inductor and a parallel circuit of a capacitor and a fluorescent lamp. An inverter in the electronic ballast is designed as a switch bridge arrangement having two switch branches and two capacitor branches whose bridge terminals which form the output of the inverter are formed, first, by the common junctions of the two switch branches and, second, by the two capacitor branches, whereby the two switch branches are composed of electronic switches having freewheeling diodes connected in parallel, these swi-tches being opened and closed in push-pull fashion having a swltching frequency that is high ln comparison to the alternating frequency o the AC source.
A prior art electronic ballasts o~ this type are disclosed, for example, by the European reference EP O 121 917 A1. The switch bridge arrangement used has onl~ one capacitor branch. This, however, is only an economic structure of such a switch bridge arrangemen-t as shown, for example, by the reference of C.H. Sturm, "Vorschaltgeraete und Schaltungen fuer Niederspannungs-Entladungslampen", Brown, Boveri & Cie AG, Mannheim, 5th Edition, ~974, pages 343 and 344.
~29t793i~
High-voltage elec-trolyte capacitors which are used in such electronic ballasts for smoothing the rectified line alternating current are designed for a direct voltage of 450 V and represent a standard that has been tested extensively. This electrical voltage of 450 V DC
is completely adequate in view of a paak line voltage of 439 V that results from a line alternating voltage of 277 V plus or minus 12~. When, however, additional measures are taken for increasing the power factor, then either a high-voltage electrolyte capacitor having a significantly higher direct voltage tolerance or, two series-connected electroly-te capacitors must be utilized.
The series connection of two electrolyte capacitors, however, also increases the costs of such an electronic ballast and also causes additional losses in view of the necessary compensation of leakage curren-t.
MMARY OF THE INVENTION
An object of the present invention is to provide an electronic ballast of the type initially cited that has an electric tolerance o at least 750 V in vlew of an increase in -the power factor and utilizes only one high-voltage electrolyte capacitor having a standard electric rating of ~50 V DC.
In an electronic ballas-t of the present invention, this object is achieved by an elec-tronic ballast for ~luorescent lamps, having an inver-ter that has its input side connected to an AC line via a series connection of a harmonic filter and a rectifier and that has its output side connected to at least one load circuit composed of a series circuit of an inductor and a parallel circuit 33~
composed of a capacitor and of a 1uorescent lamp. The inverter is fashioned as a switch bridge arrangement having two switch branches and two capacitor branches whose bridge terminals forming the output of the inver~er are formed by the common junction of the two switch branches and by the common junction of the two capacitor branches. The two switch branches are composed of electronic switches having freewheeling diodes connected in parallel with the electronic switches, the switches being opened and closed in a push-pull fashion with a switching frequency that is high in comparison to the AC
line frequency. The electronic ballast has a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement. The storage capacitor has a value such that it is not Eully charge-reversible at the line AC requency. Another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that i8 fully charge-reversible at the switching requency o the switches. An auxiliary inductor is connected in the conneating path between the rectifier and the inverter.
The harmonlc 11ter has at least a fllter lnductor in at least a parallel arm ther00f, the filter inductor in the parallel arm at an output side o the harmonic filter being effectlve across the rectifier as a preceding inductance for the inverter.
The present invention is based on the critical perception that the storage capacitor required for smoothing the rectified alternating voltage need not be ~297936 connected in parallel -to the rectifier output bu-t can also be connected in series with the load circuit. This means that the rectified AC voltage now occurs at the series connection of the two capacitor branches of the switch bridge arrangement and the high-voltage electrolyte capacitor can have a significantly lower electric rating than the electric tolerance required for the circuit. What is important in this context is that the other capacitor branch of the switch bridge arrangement need not be an electrolyte capacitor, since the aapacitor in this capacitor branch need only be dimensioned ~or a value at which its charge reversal is guaranteed at the switching frequency. In other words, the capacitor of this capacitor branch is several orders of magnitude smaller than the capacitor ln the other capacitor branch that has the high-voltage electrolyte capacitor. Thus, the series circuit o the capacitors in the two capacitor branches does not require any compensatlon for leakage current.
Compared to known circuit arrangements of this type, the circuit of the present invention requires a freewheeling diode only in parallel to the capacitor branch that does not have the high-voltage electrolyte capacitor. This freewheeli.ng diode assures that the current in the load circuit does not go to zero at the zero crossings of the AC line voltage.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with ~29~93~
further objects and advantages, may best be understood by reference to the following description taken in conjunction with -the accompanying drawings, in the several Figures in which like reference numerals identify like elements, and in which:
Figure 1 through Figure 4 are circuit diagrams depicting the functioning of the circuit of the present invention in the individual switching phases of the switch bridge arrangement in that instance wherein the level of the AC line voltage is greater than the voltage at the high-voltage electrolyte capacitor;
Figure 5 through Figure 8 are circuit diagrams depicting the functioning circuit of the present invention in the individual switch phases of the swi-tch bridge arrangemen~ in that instance wherein the level of the AC line voltage is smaller than the voltage at the high-voltage electroly-te capacitor;
Flgure 9 is a current/voltage time diagram corresponding to Figures l through 4;
Figure lO is a current/voltage time diagram correspondiny to the Figures 5 through 8;
Figure 11 is a circuit diagram depicti.ng a modifica-tion of the circult shown in Figures 1 through 8; and Figure 12 is a circuit diagram depicting a special embodiment o~ a harmonic filter shown in Figures 1 through 8.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Figures l through 8 and 11 each respectively show the circuit of an electronic ballas-t composed of a series connection of a harmonic filter HF that has its inpu-t ~2~37~3~
side connected to the line voltage N, of a rectifier GL
and of an inverter WR whose load circuit is composed o~
an inductor L in series with a parallel circuit composed of a fluorescent lamp LL and o~ an ignition capacitor C2 .
The inverter WR itself represents a switch bridge arrangement having two switch branches and two capacitor branches. The first switch branch is formed by an electronically controlled switch T1 and the second switch branch i5 formed by an electronically controlled switch T2. In a corresponding fashion, the first capacitor branch is formed by the capacitor C1 and the second capacitor branch is formed by the capacitor C2. The capacitor C2 is a high-voltage electrolyte capacitor that is selected of such size in view of the rectified AC line voltage that it is not fully charge-reversible at the AC
line frequency. The capacitor C1 is much smaller in value than the capacitor C2 and is dimensioned such that it can be fully charge-reversed during the alternating of the switches T1 and T2 that are opened and closed with a switching frequency that is much higher in comparison to the AC line frequenc~.
The inverter further has three freewheeling diodes D1, D2 and D3. The freewheeling diode D1 is connected in parallel to the switch T1, the freewheeling diode D2 is connected in parallel to the switch T2 and the freewheeling diode D3 is connected in parallel to the capacitor C1. The freewheeling diodes D1 through D3 are each respectively polarized such that they are biased in a non-conducting direction by the rectified AC voltage at the outpu-t of the rectifier GL. Figures 1 through 8 ~2~ 36 and 11 ~ur-ther depict the current 10wing through the inductor as IL and the voltages across the switch Tl and the capacitor C3 by arrows U21 and U22, respectively~
The circuit diagrams of Figures 1 through 4 that set forth the functioning of the ballast and correspond to the individual switch phases of the switches Tl and T2 are directed to that instance wherein the level of the line voltage N is higher than the voltage U22 across the capacitor C2. Figure 9 shows the current/voltage time diagram correspon.ding to these figures. In the diagram of Figure 9, the current IN through the inductor L is referenced with a solid line, the rectified current IN
deriving from the line current is referenced with a dot-dash line, the current IC1 through the capacitor C1 is referenced with a dotted line, the current IC2 through the capacitor C2 is referenced with a line interrupted by circles and the voltage U21 across the switch T2 is referenced with a dashed line.
Figure 1 shows that phase wherein the switah Tl is opened and the switch T2 is closed. ~t point ln time tO
according to Figure 9, the current IL through the inductor L, this current belng equal to the current IC2, passes through zero and reverses its direction. The current IC2 flows out o~ the capaaitor C2 through the fluorescent tube LL, the inductor L, the switch T1 and back to the capacitor C2. The capaci-tor C2 is thereby somewhat discharged and the inductor L is simultaneously charged.
In the short switch phase following thereupon that is shown in Figure 2 and in which both switches T1 and 793~
~ are opened, ths energy stored in the inductor L
discharges in the form of the current IC1 via the freewheeling diode Dl, the capacitor C1, -the fluorescent tube LL and the inductor L. The capacitor C1 is thereby charged and the voltage at the series circuit of the capacitors C1 and C2 rises above the momentary value of the AC line N. The rectifier GL thereby remains inhibited. In the diagram of Figure 9, this corresponds to the time range around point in time tl.
In the following time interval between points tl and t3, the switch positions of the switches T1 and T2 corresponding to Figure 1 reverse. This case is shown in Figure 3. The switch tl that is now closed initiates a current IC1 that flows from the capacitor C1 via the switch Tl, the inductor L and the fluorescent tube LL
back to the capacitor C1. The capacitor C1 thereby discharges. The voltage at the series circuit of the capacitors C1 and C2 thereby decreases. As soon as the voltage at the series circuit of the capacitors Cl and C2 decreases below the momentary amount of the AC line N, the reatifier Gh becomes conductive and the current IN flows from the llne N via the switch Tl, the inductor L, the fluorescent tube LL, the aapacitor C2 back into the line N during the time interval between t2 and t3 as shown in the time diagram in Figure 9. In contrast to the current IC1 illustrated with a broken line, the currant IN is illustrated with a dotted line in Figure 3.
At point in time T3 according to the diagram of Figure 9, both switches T1 and T2 re-turn to the open ~2~3~9~
condition. This switch situation is shown in Figure 4.
The current from the line N proceeds toward zero and the energy stored in the inductor L in the form of the current IC2 via the fluorescent tube LL,, the capacitor C2 and the freewheeling diode D2. In the following phase wherein the switch T2 is closed, the current IC2 that is identical to the current IL through the inductor L first approaches zero before reversing, as has already been set forth in conjunction with Figure 1.
Figures 5 through 8, corresponding to Figures 1 through 4, set forth the functioning of the ballast in instances wherein the level of the ~C line is less than or equal to the voltage U22 at the capacitor C2.
Figure 10 shows the associated current/voltage time diagram for the currents IL, IC1, IC2 and ID3 as well as of the voltage U21. What is thereby the determining actor is again the time span between tO and t4. Again, the current IL is indicated by a solid line, the current IC1 is indicated by a dotted line, the current IC2 is indicated by a line interrupted by circles, the current ID3 is indicated by a dot-dash line and the voltage U21 is indicated by a dashed line.
As shown in Figure 5 the current IC2 flows when the switch T1 is opened and the swltch T2 i8 closed. The course in this switching phase is shown in Figure 10 in the time interval ~rom tO through tl. The current IC2 flows out of the capacitor C2 through the fluorescent tube LL, the inductor L, the switch T2 and back to the capacitor C2. The capacitor C2 is thereby somewhat discharged and the inductor L is charged.
1~7~336 In the brlef switching phase in the time interval around tl as shown in Figure 10 and Figure 6 and wherein the two switches tl and t2 are opened, the energy stored in -the inductor L discharges in the form of the current IC1 via the freewheeling diode Dl, the capacitor C1 and the fluorescent tube LL. The capacitor Cl is thereby charged. In the following switch phase that is shown in Figure 7 and wherein the switch T2 is opened and the switch Tl is closed, a current initially flows out of the capacitor C1 in the time interval tl through t2 as shown in Figure 10 via the switch Tl, the inductor L and the fluorescent tube LL and back to the capacitor C1. The inductor L is thereby charged and the capacitor C1 is discharged. At point in time t2 the capacitor C1 is discharged and the inductor L continues to partially discharge via the fluorescent tube LL, the freewheeling diode D3 and the switch T1 that is still conductive. In contrast to the current IC1, this current ID3 is shown with a dotted line in Figure 7.
Figure 8 shows the short switch phase that now follows in the time interval around the point in time t3 wherein both switches T1 and T2 are opened. The currents IC1 and ID3 according to Figure 7 were in-terrupted when the switch T1 opened and the residual energ~ stored in the inductor L discharged via the fluorescent tube LL, the capacitor C2 and the freewheeling diode D2, discharging in the form of the current IC2. At point in time t~ whersin the current IL passes through zero and reverses, the switch T2 that is now again closed becomes effective as depicted in Figure 5 with the conditions of current conduction as shown in Figure 5 and occurs as has already been set forth above.
The circuit depicted in Figure 11 differs from the circuits in Figures 1 through 8 in that an auxiliary inductor Lz is provided in the connecting path between the rectifier GL and the inverter WR. As investigations have shown, the inductively loaded input of the inverter WR. As investigations have shown, the inductively loaded input of the inverter achieves times and forms of current flow that have better noise suppression. It also becomes possible to select a smaller ignition capacitor Cz.
As shall be briefly set forth with reference to Figure 12, the inductive load of the input of the inverter can also be produced without the auxiliary inductance Lz shown in Figure 11. Figure 12 shows a standard harmonic filter HF in the orm of a symmetrical T-element having filter inductors LOl and L02 in parallel branches at the input side and output side and a filter capacitor CO in a shunt arm. As a shunt arm in such a harmonic filter HF, the fllter capacitor CO' is also additionally provided at the output side and provides an additional smoothlng function for the harmonics. When the filter capaaitor CO' is omitted, than the filter inductor L02 at the output side is effective in view of the input of the inverter W~, and thus represents an inductive input load that makes the auxiliary inductor Lz superfluous.
~297~3~
The invention is not limited to the particular details of the apparatus depicted and other modifications and applications are contemplated. Certain other changes may be made in the above described apparatus without departing from the true spirit and scope of the invention herein involved. It is intended, therefore, that the subject matter in the above depiction shall be interpreted as illustra-tive and not in a limiting sense.
The present inven~ion is directed to an electronic ballast for fluorescent lamps, and in particular electronic ballasts having an inverter that has its input side connected to an AC source via a series connection of a harmonic filter and of a rectifier. Such an electronic ballast has lts output side connected to at leas-t one load circuit composed of a series circuit of an inductor and a parallel circuit of a capacitor and a fluorescent lamp. An inverter in the electronic ballast is designed as a switch bridge arrangement having two switch branches and two capacitor branches whose bridge terminals which form the output of the inverter are formed, first, by the common junctions of the two switch branches and, second, by the two capacitor branches, whereby the two switch branches are composed of electronic switches having freewheeling diodes connected in parallel, these swi-tches being opened and closed in push-pull fashion having a swltching frequency that is high ln comparison to the alternating frequency o the AC source.
A prior art electronic ballasts o~ this type are disclosed, for example, by the European reference EP O 121 917 A1. The switch bridge arrangement used has onl~ one capacitor branch. This, however, is only an economic structure of such a switch bridge arrangemen-t as shown, for example, by the reference of C.H. Sturm, "Vorschaltgeraete und Schaltungen fuer Niederspannungs-Entladungslampen", Brown, Boveri & Cie AG, Mannheim, 5th Edition, ~974, pages 343 and 344.
~29t793i~
High-voltage elec-trolyte capacitors which are used in such electronic ballasts for smoothing the rectified line alternating current are designed for a direct voltage of 450 V and represent a standard that has been tested extensively. This electrical voltage of 450 V DC
is completely adequate in view of a paak line voltage of 439 V that results from a line alternating voltage of 277 V plus or minus 12~. When, however, additional measures are taken for increasing the power factor, then either a high-voltage electrolyte capacitor having a significantly higher direct voltage tolerance or, two series-connected electroly-te capacitors must be utilized.
The series connection of two electrolyte capacitors, however, also increases the costs of such an electronic ballast and also causes additional losses in view of the necessary compensation of leakage curren-t.
MMARY OF THE INVENTION
An object of the present invention is to provide an electronic ballast of the type initially cited that has an electric tolerance o at least 750 V in vlew of an increase in -the power factor and utilizes only one high-voltage electrolyte capacitor having a standard electric rating of ~50 V DC.
In an electronic ballas-t of the present invention, this object is achieved by an elec-tronic ballast for ~luorescent lamps, having an inver-ter that has its input side connected to an AC line via a series connection of a harmonic filter and a rectifier and that has its output side connected to at least one load circuit composed of a series circuit of an inductor and a parallel circuit 33~
composed of a capacitor and of a 1uorescent lamp. The inverter is fashioned as a switch bridge arrangement having two switch branches and two capacitor branches whose bridge terminals forming the output of the inver~er are formed by the common junction of the two switch branches and by the common junction of the two capacitor branches. The two switch branches are composed of electronic switches having freewheeling diodes connected in parallel with the electronic switches, the switches being opened and closed in a push-pull fashion with a switching frequency that is high in comparison to the AC
line frequency. The electronic ballast has a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement. The storage capacitor has a value such that it is not Eully charge-reversible at the line AC requency. Another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that i8 fully charge-reversible at the switching requency o the switches. An auxiliary inductor is connected in the conneating path between the rectifier and the inverter.
The harmonlc 11ter has at least a fllter lnductor in at least a parallel arm ther00f, the filter inductor in the parallel arm at an output side o the harmonic filter being effectlve across the rectifier as a preceding inductance for the inverter.
The present invention is based on the critical perception that the storage capacitor required for smoothing the rectified alternating voltage need not be ~297936 connected in parallel -to the rectifier output bu-t can also be connected in series with the load circuit. This means that the rectified AC voltage now occurs at the series connection of the two capacitor branches of the switch bridge arrangement and the high-voltage electrolyte capacitor can have a significantly lower electric rating than the electric tolerance required for the circuit. What is important in this context is that the other capacitor branch of the switch bridge arrangement need not be an electrolyte capacitor, since the aapacitor in this capacitor branch need only be dimensioned ~or a value at which its charge reversal is guaranteed at the switching frequency. In other words, the capacitor of this capacitor branch is several orders of magnitude smaller than the capacitor ln the other capacitor branch that has the high-voltage electrolyte capacitor. Thus, the series circuit o the capacitors in the two capacitor branches does not require any compensatlon for leakage current.
Compared to known circuit arrangements of this type, the circuit of the present invention requires a freewheeling diode only in parallel to the capacitor branch that does not have the high-voltage electrolyte capacitor. This freewheeli.ng diode assures that the current in the load circuit does not go to zero at the zero crossings of the AC line voltage.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with ~29~93~
further objects and advantages, may best be understood by reference to the following description taken in conjunction with -the accompanying drawings, in the several Figures in which like reference numerals identify like elements, and in which:
Figure 1 through Figure 4 are circuit diagrams depicting the functioning of the circuit of the present invention in the individual switching phases of the switch bridge arrangement in that instance wherein the level of the AC line voltage is greater than the voltage at the high-voltage electrolyte capacitor;
Figure 5 through Figure 8 are circuit diagrams depicting the functioning circuit of the present invention in the individual switch phases of the swi-tch bridge arrangemen~ in that instance wherein the level of the AC line voltage is smaller than the voltage at the high-voltage electroly-te capacitor;
Flgure 9 is a current/voltage time diagram corresponding to Figures l through 4;
Figure lO is a current/voltage time diagram correspondiny to the Figures 5 through 8;
Figure 11 is a circuit diagram depicti.ng a modifica-tion of the circult shown in Figures 1 through 8; and Figure 12 is a circuit diagram depicting a special embodiment o~ a harmonic filter shown in Figures 1 through 8.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Figures l through 8 and 11 each respectively show the circuit of an electronic ballas-t composed of a series connection of a harmonic filter HF that has its inpu-t ~2~37~3~
side connected to the line voltage N, of a rectifier GL
and of an inverter WR whose load circuit is composed o~
an inductor L in series with a parallel circuit composed of a fluorescent lamp LL and o~ an ignition capacitor C2 .
The inverter WR itself represents a switch bridge arrangement having two switch branches and two capacitor branches. The first switch branch is formed by an electronically controlled switch T1 and the second switch branch i5 formed by an electronically controlled switch T2. In a corresponding fashion, the first capacitor branch is formed by the capacitor C1 and the second capacitor branch is formed by the capacitor C2. The capacitor C2 is a high-voltage electrolyte capacitor that is selected of such size in view of the rectified AC line voltage that it is not fully charge-reversible at the AC
line frequency. The capacitor C1 is much smaller in value than the capacitor C2 and is dimensioned such that it can be fully charge-reversed during the alternating of the switches T1 and T2 that are opened and closed with a switching frequency that is much higher in comparison to the AC line frequenc~.
The inverter further has three freewheeling diodes D1, D2 and D3. The freewheeling diode D1 is connected in parallel to the switch T1, the freewheeling diode D2 is connected in parallel to the switch T2 and the freewheeling diode D3 is connected in parallel to the capacitor C1. The freewheeling diodes D1 through D3 are each respectively polarized such that they are biased in a non-conducting direction by the rectified AC voltage at the outpu-t of the rectifier GL. Figures 1 through 8 ~2~ 36 and 11 ~ur-ther depict the current 10wing through the inductor as IL and the voltages across the switch Tl and the capacitor C3 by arrows U21 and U22, respectively~
The circuit diagrams of Figures 1 through 4 that set forth the functioning of the ballast and correspond to the individual switch phases of the switches Tl and T2 are directed to that instance wherein the level of the line voltage N is higher than the voltage U22 across the capacitor C2. Figure 9 shows the current/voltage time diagram correspon.ding to these figures. In the diagram of Figure 9, the current IN through the inductor L is referenced with a solid line, the rectified current IN
deriving from the line current is referenced with a dot-dash line, the current IC1 through the capacitor C1 is referenced with a dotted line, the current IC2 through the capacitor C2 is referenced with a line interrupted by circles and the voltage U21 across the switch T2 is referenced with a dashed line.
Figure 1 shows that phase wherein the switah Tl is opened and the switch T2 is closed. ~t point ln time tO
according to Figure 9, the current IL through the inductor L, this current belng equal to the current IC2, passes through zero and reverses its direction. The current IC2 flows out o~ the capaaitor C2 through the fluorescent tube LL, the inductor L, the switch T1 and back to the capacitor C2. The capaci-tor C2 is thereby somewhat discharged and the inductor L is simultaneously charged.
In the short switch phase following thereupon that is shown in Figure 2 and in which both switches T1 and 793~
~ are opened, ths energy stored in the inductor L
discharges in the form of the current IC1 via the freewheeling diode Dl, the capacitor C1, -the fluorescent tube LL and the inductor L. The capacitor C1 is thereby charged and the voltage at the series circuit of the capacitors C1 and C2 rises above the momentary value of the AC line N. The rectifier GL thereby remains inhibited. In the diagram of Figure 9, this corresponds to the time range around point in time tl.
In the following time interval between points tl and t3, the switch positions of the switches T1 and T2 corresponding to Figure 1 reverse. This case is shown in Figure 3. The switch tl that is now closed initiates a current IC1 that flows from the capacitor C1 via the switch Tl, the inductor L and the fluorescent tube LL
back to the capacitor C1. The capacitor C1 thereby discharges. The voltage at the series circuit of the capacitors C1 and C2 thereby decreases. As soon as the voltage at the series circuit of the capacitors Cl and C2 decreases below the momentary amount of the AC line N, the reatifier Gh becomes conductive and the current IN flows from the llne N via the switch Tl, the inductor L, the fluorescent tube LL, the aapacitor C2 back into the line N during the time interval between t2 and t3 as shown in the time diagram in Figure 9. In contrast to the current IC1 illustrated with a broken line, the currant IN is illustrated with a dotted line in Figure 3.
At point in time T3 according to the diagram of Figure 9, both switches T1 and T2 re-turn to the open ~2~3~9~
condition. This switch situation is shown in Figure 4.
The current from the line N proceeds toward zero and the energy stored in the inductor L in the form of the current IC2 via the fluorescent tube LL,, the capacitor C2 and the freewheeling diode D2. In the following phase wherein the switch T2 is closed, the current IC2 that is identical to the current IL through the inductor L first approaches zero before reversing, as has already been set forth in conjunction with Figure 1.
Figures 5 through 8, corresponding to Figures 1 through 4, set forth the functioning of the ballast in instances wherein the level of the ~C line is less than or equal to the voltage U22 at the capacitor C2.
Figure 10 shows the associated current/voltage time diagram for the currents IL, IC1, IC2 and ID3 as well as of the voltage U21. What is thereby the determining actor is again the time span between tO and t4. Again, the current IL is indicated by a solid line, the current IC1 is indicated by a dotted line, the current IC2 is indicated by a line interrupted by circles, the current ID3 is indicated by a dot-dash line and the voltage U21 is indicated by a dashed line.
As shown in Figure 5 the current IC2 flows when the switch T1 is opened and the swltch T2 i8 closed. The course in this switching phase is shown in Figure 10 in the time interval ~rom tO through tl. The current IC2 flows out of the capacitor C2 through the fluorescent tube LL, the inductor L, the switch T2 and back to the capacitor C2. The capacitor C2 is thereby somewhat discharged and the inductor L is charged.
1~7~336 In the brlef switching phase in the time interval around tl as shown in Figure 10 and Figure 6 and wherein the two switches tl and t2 are opened, the energy stored in -the inductor L discharges in the form of the current IC1 via the freewheeling diode Dl, the capacitor C1 and the fluorescent tube LL. The capacitor Cl is thereby charged. In the following switch phase that is shown in Figure 7 and wherein the switch T2 is opened and the switch Tl is closed, a current initially flows out of the capacitor C1 in the time interval tl through t2 as shown in Figure 10 via the switch Tl, the inductor L and the fluorescent tube LL and back to the capacitor C1. The inductor L is thereby charged and the capacitor C1 is discharged. At point in time t2 the capacitor C1 is discharged and the inductor L continues to partially discharge via the fluorescent tube LL, the freewheeling diode D3 and the switch T1 that is still conductive. In contrast to the current IC1, this current ID3 is shown with a dotted line in Figure 7.
Figure 8 shows the short switch phase that now follows in the time interval around the point in time t3 wherein both switches T1 and T2 are opened. The currents IC1 and ID3 according to Figure 7 were in-terrupted when the switch T1 opened and the residual energ~ stored in the inductor L discharged via the fluorescent tube LL, the capacitor C2 and the freewheeling diode D2, discharging in the form of the current IC2. At point in time t~ whersin the current IL passes through zero and reverses, the switch T2 that is now again closed becomes effective as depicted in Figure 5 with the conditions of current conduction as shown in Figure 5 and occurs as has already been set forth above.
The circuit depicted in Figure 11 differs from the circuits in Figures 1 through 8 in that an auxiliary inductor Lz is provided in the connecting path between the rectifier GL and the inverter WR. As investigations have shown, the inductively loaded input of the inverter WR. As investigations have shown, the inductively loaded input of the inverter achieves times and forms of current flow that have better noise suppression. It also becomes possible to select a smaller ignition capacitor Cz.
As shall be briefly set forth with reference to Figure 12, the inductive load of the input of the inverter can also be produced without the auxiliary inductance Lz shown in Figure 11. Figure 12 shows a standard harmonic filter HF in the orm of a symmetrical T-element having filter inductors LOl and L02 in parallel branches at the input side and output side and a filter capacitor CO in a shunt arm. As a shunt arm in such a harmonic filter HF, the fllter capacitor CO' is also additionally provided at the output side and provides an additional smoothlng function for the harmonics. When the filter capaaitor CO' is omitted, than the filter inductor L02 at the output side is effective in view of the input of the inverter W~, and thus represents an inductive input load that makes the auxiliary inductor Lz superfluous.
~297~3~
The invention is not limited to the particular details of the apparatus depicted and other modifications and applications are contemplated. Certain other changes may be made in the above described apparatus without departing from the true spirit and scope of the invention herein involved. It is intended, therefore, that the subject matter in the above depiction shall be interpreted as illustra-tive and not in a limiting sense.
Claims (5)
1. An electronic ballast for fluorescent lamps, having an inverter that has its input side connected to an AC line via a series connection of a harmonic filter and a rectifier and that has its output side connected to at least one load circuit composed of a series circuit of an inductor and a parallel circuit composed of a capacitor and of a fluorescent lamp, whereby the inverter is fashioned as a switch bridge arrangement having two switch branches and two capacitor branches whose bridge terminals forming the output of the inverter are formed by the common junction of the two switch branches and by the common junction of the two capacitor branches, and whereby the two switch branches are composed of electronic switches having freewheeling diodes connected in parallel with the electronic switches, the switches being opened and closed in a push-pull fashion with a switching frequency that is high in comparison to the AC
line frequency, comprising a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement; the storage capacitor having a value such that it is not fully charge-reversible at the line AC frequency, whereas another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that is fully charge-reversible at the switching frequency of the switches.
line frequency, comprising a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement; the storage capacitor having a value such that it is not fully charge-reversible at the line AC frequency, whereas another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that is fully charge-reversible at the switching frequency of the switches.
2. The electronic ballast means according to claim 1, wherein an auxiliary inductor is connected in the connecting path between the rectifier and the inverter.
3. The electronic ballast means according to claim 1, wherein the harmonic filter has at least a filter inductor in at least a parallel arm thereof and wherein the filter inductor in the parallel arm at an output side of the harmonic filter is effective across the rectifier as a preceding inductance for the inverter.
4. An electronic ballast for fluorescent lamps, having an inverter that has its input side connected to an AC line via a series connection of a harmonic filter and a rectifier and that has its output side connected to at least one load circuit composed of a series circuit of an inductor and a parallel circuit composed of a capacitor and of a fluorescent lamp, whereby the inverter is fashioned as a switch bridge arrangement having two switch branches and two capacitor branches whose bridge terminals forming the output of the inverter are formed by the common junction of the two switch branches and by the common junction of the two capacitor branches, and whereby the two switch branches are composed of electronic switches having freewheeling diodes connected in parallel with the electronic switches, the switches being opened and closed in a push-pull fashion with a switching frequency that is high in comparison to the AC
line frequency, comprising a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement; the storage capacitor having a value such that it is not fully charge-reversible at the line AC frequency, whereas another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that is fully charge-reversible at the switching frequency of the switches; an auxiliary inductor being connected in the connecting path between the rectifier and the inverter.
line frequency, comprising a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement; the storage capacitor having a value such that it is not fully charge-reversible at the line AC frequency, whereas another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that is fully charge-reversible at the switching frequency of the switches; an auxiliary inductor being connected in the connecting path between the rectifier and the inverter.
5. An electronic ballast for fluorescent lamps, having an inverter that has its input side connected to an AC line via a series connection of a harmonic filter and a rectifier and that has its output side connected to at least one load circuit composed of a series circuit of an inductor and a parallel circuit composed of a capacitor and of a fluorescent lamp, whereby the inverter is fashioned as a switch bridge arrangement having two switch branches and two capacitor branches whose bridge terminals forming the output of the inverter are formed by the common junction of the two switch branches and by the common junction of the two capacitor branches, and whereby the two switch branches are composed of electronic switches having freewheeling diodes connected in parallel with the electronic switches, the switches being opened and closed in a push-pull fashion with a switching frequency that is high in comparison to the AC
line frequency, comprising a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement; the storage capacitor having a value such that it is not fully charge-reversible at the line AC frequency, whereas another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that is fully charge-reversible at the switching frequency of the switches; the harmonic filter having at least a filter inductor in at least a parallel arm thereof, the filter inductor in the parallel arm at an output side of the harmonic filter being effective across the rectifier as a preceding inductance for the inverter.
line frequency, comprising a storage capacitor required for the smoothing of the AC rectified line voltage connected in one of the capacitor branches of the switch bridge arrangement; the storage capacitor having a value such that it is not fully charge-reversible at the line AC frequency, whereas another capacitor in the other capacitor branch has a freewheeling diode connected parallel thereto and is only of such a size that is fully charge-reversible at the switching frequency of the switches; the harmonic filter having at least a filter inductor in at least a parallel arm thereof, the filter inductor in the parallel arm at an output side of the harmonic filter being effective across the rectifier as a preceding inductance for the inverter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3825513.8 | 1988-07-27 | ||
| DE3825513 | 1988-07-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1297936C true CA1297936C (en) | 1992-03-24 |
Family
ID=6359678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000606557A Expired - Fee Related CA1297936C (en) | 1988-07-27 | 1989-07-25 | Electronic ballast for fluorescent lamps |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4996462A (en) |
| EP (1) | EP0352703B1 (en) |
| JP (1) | JPH0834127B2 (en) |
| AT (1) | ATE99487T1 (en) |
| CA (1) | CA1297936C (en) |
| DE (1) | DE58906543D1 (en) |
| HK (1) | HK123295A (en) |
| ZA (1) | ZA895678B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6495969B1 (en) * | 1987-08-03 | 2002-12-17 | Ole K. Nilssen | Series-resonant ballast having overload control |
| US5068573A (en) * | 1990-09-20 | 1991-11-26 | North American Philips Corporation | Power supply with energy storage for improved voltage regulation |
| FI87412C (en) * | 1991-02-25 | 1992-12-28 | Kemppi Oy | SVETSNINGSINVERTER OCH FOERFARANDE FOER STYRNING AV SVETSNINGSINVERTER |
| US5267134A (en) * | 1991-09-19 | 1993-11-30 | Aziz Banayan | Voltage and frequency converter device |
| DE4228682A1 (en) * | 1992-08-28 | 1994-03-03 | Tridonic Bauelemente Gmbh Dorn | Ballast for a gas discharge lamp with an inverter circuit |
| US5351180A (en) * | 1992-10-30 | 1994-09-27 | Electric Power Research Institute, Inc. | Highly fault tolerant active power line conditioner |
| US5345377A (en) * | 1992-10-30 | 1994-09-06 | Electric Power Research Institute, Inc. | Harmonic controller for an active power line conditioner |
| US5287288A (en) * | 1992-10-30 | 1994-02-15 | Electric Power Research Institute, Inc. | Active power line conditioner with low cost surge protection and fast overload recovery |
| US5384696A (en) * | 1992-10-30 | 1995-01-24 | Electric Power Research Institute, Inc. | Active power line conditioner with fundamental negative sequence compensation |
| JPH08503117A (en) * | 1992-10-30 | 1996-04-02 | エレクトリック パワー リサーチ インスチテュート インコーポレイテッド | Synchronous conversion control type active power line regulator |
| US5351178A (en) * | 1992-10-30 | 1994-09-27 | Electric Power Research Institute, Inc. | Active power line conditioner with a derived load current fundamental signal for fast dynamic response |
| US5359275A (en) * | 1992-10-30 | 1994-10-25 | Electric Power Research Institute, Inc. | Load current fundamental filter with one cycle response |
| US5359263A (en) * | 1992-11-20 | 1994-10-25 | Remtech Company | Tuned LRC ballasting circuit for compact fluorescent lighting |
| US5351181A (en) * | 1993-03-12 | 1994-09-27 | Electric Power Research Institute, Inc. | Low cost active power line conditioner |
| US5434478A (en) * | 1993-03-29 | 1995-07-18 | Ultra-Lum, Inc. | Electronic ballast for transilluminators and crosslinkers |
| US5686799A (en) * | 1994-03-25 | 1997-11-11 | Pacific Scientific Company | Ballast circuit for compact fluorescent lamp |
| DE4410492A1 (en) * | 1994-03-25 | 1995-09-28 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Circuit arrangement for operating low-pressure discharge lamps |
| TW307980B (en) * | 1994-04-28 | 1997-06-11 | Toshiba Light Technic Kk | |
| CN1049305C (en) * | 1994-07-29 | 2000-02-09 | 东芝照明技术株式会社 | Power supply apparatus having high power-factor and low distortion-factor characteristics |
| US6037722A (en) * | 1994-09-30 | 2000-03-14 | Pacific Scientific | Dimmable ballast apparatus and method for controlling power delivered to a fluorescent lamp |
| IT1271237B (en) * | 1994-09-30 | 1997-05-27 | Whirlpool Italia | DEVICE TO CONTROL THE POWER OF HEATING ELEMENTS |
| US5821699A (en) * | 1994-09-30 | 1998-10-13 | Pacific Scientific | Ballast circuit for fluorescent lamps |
| US5691606A (en) * | 1994-09-30 | 1997-11-25 | Pacific Scientific Company | Ballast circuit for fluorescent lamp |
| US5596247A (en) * | 1994-10-03 | 1997-01-21 | Pacific Scientific Company | Compact dimmable fluorescent lamps with central dimming ring |
| US5925986A (en) * | 1996-05-09 | 1999-07-20 | Pacific Scientific Company | Method and apparatus for controlling power delivered to a fluorescent lamp |
| US5866993A (en) * | 1996-11-14 | 1999-02-02 | Pacific Scientific Company | Three-way dimming ballast circuit with passive power factor correction |
| US5798617A (en) * | 1996-12-18 | 1998-08-25 | Pacific Scientific Company | Magnetic feedback ballast circuit for fluorescent lamp |
| JP2002543571A (en) * | 1999-04-28 | 2002-12-17 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Circuit layout |
| US7122972B2 (en) * | 2003-11-10 | 2006-10-17 | University Of Hong Kong | Dimmable ballast with resistive input and low electromagnetic interference |
| DE102005034505A1 (en) * | 2005-07-20 | 2007-02-01 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Circuit arrangement with transformerless converter with choke for the pulsed operation of dielectric barrier discharge lamps |
| US8264160B2 (en) * | 2009-09-04 | 2012-09-11 | Sheng-Hann Lee | Advanced electronic ballasts |
| CN102348310B (en) | 2010-08-03 | 2013-08-14 | 英飞特电子（杭州）股份有限公司 | Multi-path LED load power supply circuit |
| CA2755178C (en) * | 2010-10-12 | 2018-01-02 | National Cheng Kung University | Full-bridge electronic ballast having simplified continuous-conduction-mode charge pump pfc circuit |
| CN102932998B (en) * | 2012-11-13 | 2014-09-17 | 镇江乐电半导体科技有限公司 | Power converter |
| US10637575B2 (en) * | 2016-05-25 | 2020-04-28 | Wisconsin Alumni Research Foundation | Spatial location indoors using standard fluorescent fixtures |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU555174B2 (en) * | 1981-09-18 | 1986-09-18 | Oy Helvar | Electronic ballast for a discharge lamp |
| GB2124042B (en) * | 1982-06-01 | 1986-10-01 | Control Logic | Reduction of harmonics in gas discharge lamp ballasts |
| DE3312574A1 (en) * | 1983-04-08 | 1984-10-18 | Trilux-Lenze Gmbh + Co Kg, 5760 Arnsberg | ELECTRONIC CONTROLLER FOR FLUORESCENT LAMPS |
| WO1985004769A1 (en) * | 1984-04-09 | 1985-10-24 | Nigg Juerg | Process for releasibly connecting electric lighting apparatuses, adapter respectively ballast and circuit with a high frequency generator |
| DE3667367D1 (en) * | 1985-06-04 | 1990-01-11 | Thorn Emi Lighting Nz Ltd | IMPROVED POWER SUPPLY. |
-
1989
- 1989-06-02 US US07/360,782 patent/US4996462A/en not_active Expired - Fee Related
- 1989-07-24 DE DE89113600T patent/DE58906543D1/en not_active Expired - Fee Related
- 1989-07-24 EP EP89113600A patent/EP0352703B1/en not_active Expired - Lifetime
- 1989-07-24 AT AT89113600T patent/ATE99487T1/en active
- 1989-07-25 CA CA000606557A patent/CA1297936C/en not_active Expired - Fee Related
- 1989-07-26 ZA ZA895678A patent/ZA895678B/en unknown
- 1989-07-27 JP JP1192788A patent/JPH0834127B2/en not_active Expired - Fee Related
-
1995
- 1995-07-27 HK HK123295A patent/HK123295A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| DE58906543D1 (en) | 1994-02-10 |
| EP0352703B1 (en) | 1993-12-29 |
| ATE99487T1 (en) | 1994-01-15 |
| ZA895678B (en) | 1990-04-25 |
| JPH0834127B2 (en) | 1996-03-29 |
| HK123295A (en) | 1995-08-04 |
| US4996462A (en) | 1991-02-26 |
| EP0352703A1 (en) | 1990-01-31 |
| JPH0275200A (en) | 1990-03-14 |
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